I'm doing tests with SashForm and it show an error in this situation:
1.Create a SWT Shell;
2.Add FillLayout;
3.Add SashForm;
4.Add a Button;
5.Add another Button in the left of the other into SashForm;

In this point, the left Button has a DragTrackerTool in the RIGHT side that allow the user to resize it.

6.Move the right Button in the place of the another button, making they change position in SashForm;

Now the new left Button doesn't have the DragTrackerTool, and the new right Button have DragTrackerTool in his right side...
Just try to resize and it will show this error:
java.lang.ArrayIndexOutOfBoundsException: 2